Plan file details
Planophore. Rubber pusher model. Wingspan 436mm.
Originally designed in 1871 by Alphonse Pénaud, this here is a later redrawn plan by Carmelo Brutaniti in 2002.
Quote: "The planophores. When Alphonse turned his attention to fixed-wing flight, he was fortunate in knowing Joseph M Pline, who was skilled in the design of tiny paper oiseaus (birds) and papillons (butterflies). Pline had painstakingly determined principles of balance, incidence, and dihedral angles in providing the automatic equilibrium so essential to Free Flight models.
By combining improved variations of Pline's self-stabilizing features with his own rubber-in-torsion motors, Penaud created the series of simple model airplane designs that he called planophores.
He experimented with contra-rotating propellers to minimize torque influences, but soon discovered much easier ways of achieving similar results. Simply adding a small amount of ballast to the model's wing tip, and/or setting one wing panel to a slightly greater incidence angle than the other, worked effectively in counteracting torque. Penaud also tried tractor (front-mounted) propellers, though he favored a single pusher for propeller protection in the event of collisions.
Although Penaud tested multiple blades, he preferred two-bladed arrangements for simplicity and damage resistance, since they could lie flat during landing. He didn't want to complicate his models or increase their weight with landing gear.
The educational and entertainment value of Penaud's models was resoundingly proven during his 1871 outdoor public demonstrations in Paris' famous Gardens of Tuileries and inside the beautiful Horticultural Hall. These demonstrations brought much favorable publicity for both the planophores and their creator.
Although planophores were constructed by Penaud and his associates, in various forms of different styles with diverse results, the most successful fliers seem to have spanned from 18 to 24 in. One 18 in span example had about a 4 in wing root chord, a 20 in long fuselage stick, and an 8 in dia propeller. The blades generally were made of paper, but sometimes of bird feathers, and the front and rear motor hooks were steel wire.
The wings were constructed from bird feather quills, pinned together and covered with goldbeater's skin. Dihedral was either in shallow V form or achieved simply by curving the wing tips gracefully upward. The wing assembly could be slid along the fuselage stick to adjust balance, and the incidence angles of the individual wing panels could be altered. The similarly constructed horizontal tail was also adjustable for inci-dence, and its tips could be raised for added stability.
Some planophores were equipped with a vertical tailplane, which Penaud likened to the steering function provided by a ship's rudder. The tailplane was rarely, if ever, shown in early illustrations."
Scan from DBHL, cleanup by theshadow.
Direct submission to Outerzone.
Update 10/10/2018: Added article, thanks to RFJ.